Maurice Maître climbing the Col du Parpaillon over military “mule paths” in the early 1930s. His 650B bike is equipped with a Cyclo derailleur, two frame mounted brakes and an additional drum brake. Maître was a prolific cyclotourist and a disciple of Vélocio, who went “mountain biking” on these same tracks some 30 years earlier. Nowadays the Route du Parpaillon is still as rough.
(thanks to Cycle de France for the picture !)